/*
 * Copyright (c) 2000, 2013, Oracle and/or its affiliates. All rights reserved.
 * ORACLE PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
 *
 *
 *
 *
 *
 *
 *
 *
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 *
 *
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 *
 *
 *
 *
 */


package javax.management.openmbean;

// java import
//

import java.lang.reflect.Array;
import java.lang.reflect.Constructor;
import java.lang.reflect.Method;
import java.lang.reflect.Modifier;
import java.util.Arrays;
import java.util.Collection;
import java.util.Collections;
import java.util.HashMap;
import java.util.HashSet;
import java.util.Map;
import java.util.Set;
import javax.management.Descriptor;
import javax.management.DescriptorRead;
import javax.management.ImmutableDescriptor;
import javax.management.MBeanAttributeInfo;
import com.sun.jmx.remote.util.EnvHelp;
import sun.reflect.misc.ConstructorUtil;
import sun.reflect.misc.MethodUtil;
import sun.reflect.misc.ReflectUtil;

/**
 * Describes an attribute of an open MBean.
 *
 * @since 1.5
 */
public class OpenMBeanAttributeInfoSupport
    extends MBeanAttributeInfo
    implements OpenMBeanAttributeInfo {

  /* Serial version */
  static final long serialVersionUID = -4867215622149721849L;

  /**
   * @serial The open mbean attribute's <i>open type</i>
   */
  private OpenType<?> openType;

  /**
   * @serial The open mbean attribute's default value
   */
  private final Object defaultValue;

  /**
   * @serial The open mbean attribute's legal values. This {@link Set} is unmodifiable
   */
  private final Set<?> legalValues;  // to be constructed unmodifiable

  /**
   * @serial The open mbean attribute's min value
   */
  private final Comparable<?> minValue;

  /**
   * @serial The open mbean attribute's max value
   */
  private final Comparable<?> maxValue;


  // As this instance is immutable, these two values need only
  // be calculated once.
  private transient Integer myHashCode = null;
  private transient String myToString = null;


  /**
   * Constructs an {@code OpenMBeanAttributeInfoSupport} instance,
   * which describes the attribute of an open MBean with the
   * specified {@code name}, {@code openType} and {@code
   * description}, and the specified read/write access properties.
   *
   * @param name cannot be a null or empty string.
   * @param description cannot be a null or empty string.
   * @param openType cannot be null.
   * @param isReadable {@code true} if the attribute has a getter exposed for management.
   * @param isWritable {@code true} if the attribute has a setter exposed for management.
   * @param isIs {@code true} if the attribute's getter is of the form <tt>is<i>XXX</i></tt>.
   * @throws IllegalArgumentException if {@code name} or {@code description} are null or empty
   * string, or {@code openType} is null.
   */
  public OpenMBeanAttributeInfoSupport(String name,
      String description,
      OpenType<?> openType,
      boolean isReadable,
      boolean isWritable,
      boolean isIs) {
    this(name, description, openType, isReadable, isWritable, isIs,
        (Descriptor) null);
  }

  /**
   * <p>Constructs an {@code OpenMBeanAttributeInfoSupport} instance,
   * which describes the attribute of an open MBean with the
   * specified {@code name}, {@code openType}, {@code
   * description}, read/write access properties, and {@code Descriptor}.</p>
   *
   * <p>The {@code descriptor} can contain entries that will define
   * the values returned by certain methods of this class, as
   * explained in the <a href="package-summary.html#constraints">
   * package description</a>.
   *
   * @param name cannot be a null or empty string.
   * @param description cannot be a null or empty string.
   * @param openType cannot be null.
   * @param isReadable {@code true} if the attribute has a getter exposed for management.
   * @param isWritable {@code true} if the attribute has a setter exposed for management.
   * @param isIs {@code true} if the attribute's getter is of the form <tt>is<i>XXX</i></tt>.
   * @param descriptor The descriptor for the attribute.  This may be null which is equivalent to an
   * empty descriptor.
   * @throws IllegalArgumentException if {@code name} or {@code description} are null or empty
   * string, or {@code openType} is null, or the descriptor entries are invalid as described in the
   * <a href="package-summary.html#constraints">package description</a>.
   * @since 1.6
   */
  public OpenMBeanAttributeInfoSupport(String name,
      String description,
      OpenType<?> openType,
      boolean isReadable,
      boolean isWritable,
      boolean isIs,
      Descriptor descriptor) {
    // Construct parent's state
    //
    super(name,
        (openType == null) ? null : openType.getClassName(),
        description,
        isReadable,
        isWritable,
        isIs,
        ImmutableDescriptor.union(descriptor, (openType == null) ? null :
            openType.getDescriptor()));

    // Initialize this instance's specific state
    //
    this.openType = openType;

    descriptor = getDescriptor();  // replace null by empty
    this.defaultValue = valueFrom(descriptor, "defaultValue", openType);
    this.legalValues = valuesFrom(descriptor, "legalValues", openType);
    this.minValue = comparableValueFrom(descriptor, "minValue", openType);
    this.maxValue = comparableValueFrom(descriptor, "maxValue", openType);

    try {
      check(this);
    } catch (OpenDataException e) {
      throw new IllegalArgumentException(e.getMessage(), e);
    }
  }

  /**
   * Constructs an {@code OpenMBeanAttributeInfoSupport} instance,
   * which describes the attribute of an open MBean with the
   * specified {@code name}, {@code openType}, {@code description}
   * and {@code defaultValue}, and the specified read/write access
   * properties.
   *
   * @param name cannot be a null or empty string.
   * @param description cannot be a null or empty string.
   * @param openType cannot be null.
   * @param isReadable {@code true} if the attribute has a getter exposed for management.
   * @param isWritable {@code true} if the attribute has a setter exposed for management.
   * @param isIs {@code true} if the attribute's getter is of the form <tt>is<i>XXX</i></tt>.
   * @param defaultValue must be a valid value for the {@code openType} specified for this
   * attribute; default value not supported for {@code ArrayType} and {@code TabularType}; can be
   * null, in which case it means that no default value is set.
   * @param <T> allows the compiler to check that the {@code defaultValue}, if non-null, has the
   * correct Java type for the given {@code openType}.
   * @throws IllegalArgumentException if {@code name} or {@code description} are null or empty
   * string, or {@code openType} is null.
   * @throws OpenDataException if {@code defaultValue} is not a valid value for the specified {@code
   * openType}, or {@code defaultValue} is non null and {@code openType} is an {@code ArrayType} or
   * a {@code TabularType}.
   */
  public <T> OpenMBeanAttributeInfoSupport(String name,
      String description,
      OpenType<T> openType,
      boolean isReadable,
      boolean isWritable,
      boolean isIs,
      T defaultValue)
      throws OpenDataException {
    this(name, description, openType, isReadable, isWritable, isIs,
        defaultValue, (T[]) null);
  }


  /**
   * <p>Constructs an {@code OpenMBeanAttributeInfoSupport} instance,
   * which describes the attribute of an open MBean with the
   * specified {@code name}, {@code openType}, {@code description},
   * {@code defaultValue} and {@code legalValues}, and the specified
   * read/write access properties.</p>
   *
   * <p>The contents of {@code legalValues} are copied, so subsequent
   * modifications of the array referenced by {@code legalValues}
   * have no impact on this {@code OpenMBeanAttributeInfoSupport}
   * instance.</p>
   *
   * @param name cannot be a null or empty string.
   * @param description cannot be a null or empty string.
   * @param openType cannot be null.
   * @param isReadable {@code true} if the attribute has a getter exposed for management.
   * @param isWritable {@code true} if the attribute has a setter exposed for management.
   * @param isIs {@code true} if the attribute's getter is of the form <tt>is<i>XXX</i></tt>.
   * @param defaultValue must be a valid value for the {@code openType} specified for this
   * attribute; default value not supported for {@code ArrayType} and {@code TabularType}; can be
   * null, in which case it means that no default value is set.
   * @param legalValues each contained value must be valid for the {@code openType} specified for
   * this attribute; legal values not supported for {@code ArrayType} and {@code TabularType}; can
   * be null or empty.
   * @param <T> allows the compiler to check that the {@code defaultValue} and {@code legalValues},
   * if non-null, have the correct Java type for the given {@code openType}.
   * @throws IllegalArgumentException if {@code name} or {@code description} are null or empty
   * string, or {@code openType} is null.
   * @throws OpenDataException if {@code defaultValue} is not a valid value for the specified {@code
   * openType}, or one value in {@code legalValues} is not valid for the specified {@code openType},
   * or {@code defaultValue} is non null and {@code openType} is an {@code ArrayType} or a {@code
   * TabularType}, or {@code legalValues} is non null and non empty and {@code openType} is an
   * {@code ArrayType} or a {@code TabularType}, or {@code legalValues} is non null and non empty
   * and {@code defaultValue} is not contained in {@code legalValues}.
   */
  public <T> OpenMBeanAttributeInfoSupport(String name,
      String description,
      OpenType<T> openType,
      boolean isReadable,
      boolean isWritable,
      boolean isIs,
      T defaultValue,
      T[] legalValues)
      throws OpenDataException {
    this(name, description, openType, isReadable, isWritable, isIs,
        defaultValue, legalValues, null, null);
  }


  /**
   * Constructs an {@code OpenMBeanAttributeInfoSupport} instance,
   * which describes the attribute of an open MBean, with the
   * specified {@code name}, {@code openType}, {@code description},
   * {@code defaultValue}, {@code minValue} and {@code maxValue}.
   *
   * It is possible to specify minimal and maximal values only for
   * an open type whose values are {@code Comparable}.
   *
   * @param name cannot be a null or empty string.
   * @param description cannot be a null or empty string.
   * @param openType cannot be null.
   * @param isReadable {@code true} if the attribute has a getter exposed for management.
   * @param isWritable {@code true} if the attribute has a setter exposed for management.
   * @param isIs {@code true} if the attribute's getter is of the form <tt>is<i>XXX</i></tt>.
   * @param defaultValue must be a valid value for the {@code openType} specified for this
   * attribute; default value not supported for {@code ArrayType} and {@code TabularType}; can be
   * null, in which case it means that no default value is set.
   * @param minValue must be valid for the {@code openType} specified for this attribute; can be
   * null, in which case it means that no minimal value is set.
   * @param maxValue must be valid for the {@code openType} specified for this attribute; can be
   * null, in which case it means that no maximal value is set.
   * @param <T> allows the compiler to check that the {@code defaultValue}, {@code minValue}, and
   * {@code maxValue}, if non-null, have the correct Java type for the given {@code openType}.
   * @throws IllegalArgumentException if {@code name} or {@code description} are null or empty
   * string, or {@code openType} is null.
   * @throws OpenDataException if {@code defaultValue}, {@code minValue} or {@code maxValue} is not
   * a valid value for the specified {@code openType}, or {@code defaultValue} is non null and
   * {@code openType} is an {@code ArrayType} or a {@code TabularType}, or both {@code minValue} and
   * {@code maxValue} are non-null and {@code minValue.compareTo(maxValue) > 0} is {@code true}, or
   * both {@code defaultValue} and {@code minValue} are non-null and {@code
   * minValue.compareTo(defaultValue) > 0} is {@code true}, or both {@code defaultValue} and {@code
   * maxValue} are non-null and {@code defaultValue.compareTo(maxValue) > 0} is {@code true}.
   */
  public <T> OpenMBeanAttributeInfoSupport(String name,
      String description,
      OpenType<T> openType,
      boolean isReadable,
      boolean isWritable,
      boolean isIs,
      T defaultValue,
      Comparable<T> minValue,
      Comparable<T> maxValue)
      throws OpenDataException {
    this(name, description, openType, isReadable, isWritable, isIs,
        defaultValue, null, minValue, maxValue);
  }

  private <T> OpenMBeanAttributeInfoSupport(String name,
      String description,
      OpenType<T> openType,
      boolean isReadable,
      boolean isWritable,
      boolean isIs,
      T defaultValue,
      T[] legalValues,
      Comparable<T> minValue,
      Comparable<T> maxValue)
      throws OpenDataException {
    super(name,
        (openType == null) ? null : openType.getClassName(),
        description,
        isReadable,
        isWritable,
        isIs,
        makeDescriptor(openType,
            defaultValue, legalValues, minValue, maxValue));

    this.openType = openType;

    Descriptor d = getDescriptor();
    this.defaultValue = defaultValue;
    this.minValue = minValue;
    this.maxValue = maxValue;
    // We already converted the array into an unmodifiable Set
    // in the descriptor.
    this.legalValues = (Set<?>) d.getFieldValue("legalValues");

    check(this);
  }

  /**
   * An object serialized in a version of the API before Descriptors were
   * added to this class will have an empty or null Descriptor.
   * For consistency with our
   * behavior in this version, we must replace the object with one
   * where the Descriptors reflect the same values of openType, defaultValue,
   * etc.
   **/
  private Object readResolve() {
    if (getDescriptor().getFieldNames().length == 0) {
      OpenType<Object> xopenType = cast(openType);
      Set<Object> xlegalValues = cast(legalValues);
      Comparable<Object> xminValue = cast(minValue);
      Comparable<Object> xmaxValue = cast(maxValue);
      return new OpenMBeanAttributeInfoSupport(
          name, description, openType,
          isReadable(), isWritable(), isIs(),
          makeDescriptor(xopenType, defaultValue, xlegalValues,
              xminValue, xmaxValue));
    } else {
      return this;
    }
  }

  static void check(OpenMBeanParameterInfo info) throws OpenDataException {
    OpenType<?> openType = info.getOpenType();
    if (openType == null) {
      throw new IllegalArgumentException("OpenType cannot be null");
    }

    if (info.getName() == null ||
        info.getName().trim().equals("")) {
      throw new IllegalArgumentException("Name cannot be null or empty");
    }

    if (info.getDescription() == null ||
        info.getDescription().trim().equals("")) {
      throw new IllegalArgumentException("Description cannot be null or empty");
    }

    // Check and initialize defaultValue
    //
    if (info.hasDefaultValue()) {
      // Default value not supported for ArrayType and TabularType
      // Cast to Object because "OpenType<T> instanceof" is illegal
      if (openType.isArray() || (Object) openType instanceof TabularType) {
        throw new OpenDataException("Default value not supported " +
            "for ArrayType and TabularType");
      }
      // Check defaultValue's class
      if (!openType.isValue(info.getDefaultValue())) {
        final String msg =
            "Argument defaultValue's class [\"" +
                info.getDefaultValue().getClass().getName() +
                "\"] does not match the one defined in openType[\"" +
                openType.getClassName() + "\"]";
        throw new OpenDataException(msg);
      }
    }

    // Check that we don't have both legalValues and min or max
    //
    if (info.hasLegalValues() &&
        (info.hasMinValue() || info.hasMaxValue())) {
      throw new OpenDataException("cannot have both legalValue and " +
          "minValue or maxValue");
    }

    // Check minValue and maxValue
    if (info.hasMinValue() && !openType.isValue(info.getMinValue())) {
      final String msg =
          "Type of minValue [" + info.getMinValue().getClass().getName() +
              "] does not match OpenType [" + openType.getClassName() + "]";
      throw new OpenDataException(msg);
    }
    if (info.hasMaxValue() && !openType.isValue(info.getMaxValue())) {
      final String msg =
          "Type of maxValue [" + info.getMaxValue().getClass().getName() +
              "] does not match OpenType [" + openType.getClassName() + "]";
      throw new OpenDataException(msg);
    }

    // Check that defaultValue is a legal value
    //
    if (info.hasDefaultValue()) {
      Object defaultValue = info.getDefaultValue();
      if (info.hasLegalValues() &&
          !info.getLegalValues().contains(defaultValue)) {
        throw new OpenDataException("defaultValue is not contained " +
            "in legalValues");
      }

      // Check that minValue <= defaultValue <= maxValue
      //
      if (info.hasMinValue()) {
        if (compare(info.getMinValue(), defaultValue) > 0) {
          throw new OpenDataException("minValue cannot be greater " +
              "than defaultValue");
        }
      }
      if (info.hasMaxValue()) {
        if (compare(info.getMaxValue(), defaultValue) < 0) {
          throw new OpenDataException("maxValue cannot be less " +
              "than defaultValue");
        }
      }
    }

    // Check legalValues
    //
    if (info.hasLegalValues()) {
      // legalValues not supported for TabularType and arrays
      if ((Object) openType instanceof TabularType || openType.isArray()) {
        throw new OpenDataException("Legal values not supported " +
            "for TabularType and arrays");
      }
      // Check legalValues are valid with openType
      for (Object v : info.getLegalValues()) {
        if (!openType.isValue(v)) {
          final String msg =
              "Element of legalValues [" + v +
                  "] is not a valid value for the specified openType [" +
                  openType.toString() + "]";
          throw new OpenDataException(msg);
        }
      }
    }

    // Check that, if both specified, minValue <= maxValue
    //
    if (info.hasMinValue() && info.hasMaxValue()) {
      if (compare(info.getMinValue(), info.getMaxValue()) > 0) {
        throw new OpenDataException("minValue cannot be greater " +
            "than maxValue");
      }
    }

  }

  @SuppressWarnings({"unchecked", "rawtypes"})
  static int compare(Object x, Object y) {
    return ((Comparable) x).compareTo(y);
  }

  static <T> Descriptor makeDescriptor(OpenType<T> openType,
      T defaultValue,
      T[] legalValues,
      Comparable<T> minValue,
      Comparable<T> maxValue) {
    Map<String, Object> map = new HashMap<String, Object>();
    if (defaultValue != null) {
      map.put("defaultValue", defaultValue);
    }
    if (legalValues != null) {
      Set<T> set = new HashSet<T>();
      for (T v : legalValues) {
        set.add(v);
      }
      set = Collections.unmodifiableSet(set);
      map.put("legalValues", set);
    }
    if (minValue != null) {
      map.put("minValue", minValue);
    }
    if (maxValue != null) {
      map.put("maxValue", maxValue);
    }
    if (map.isEmpty()) {
      return openType.getDescriptor();
    } else {
      map.put("openType", openType);
      return new ImmutableDescriptor(map);
    }
  }

  static <T> Descriptor makeDescriptor(OpenType<T> openType,
      T defaultValue,
      Set<T> legalValues,
      Comparable<T> minValue,
      Comparable<T> maxValue) {
    T[] legals;
    if (legalValues == null) {
      legals = null;
    } else {
      legals = cast(new Object[legalValues.size()]);
      legalValues.toArray(legals);
    }
    return makeDescriptor(openType, defaultValue, legals, minValue, maxValue);
  }


  static <T> T valueFrom(Descriptor d, String name, OpenType<T> openType) {
    Object x = d.getFieldValue(name);
    if (x == null) {
      return null;
    }
    try {
      return convertFrom(x, openType);
    } catch (Exception e) {
      final String msg =
          "Cannot convert descriptor field " + name + "  to " +
              openType.getTypeName();
      throw EnvHelp.initCause(new IllegalArgumentException(msg), e);
    }
  }

  static <T> Set<T> valuesFrom(Descriptor d, String name,
      OpenType<T> openType) {
    Object x = d.getFieldValue(name);
    if (x == null) {
      return null;
    }
    Collection<?> coll;
    if (x instanceof Set<?>) {
      Set<?> set = (Set<?>) x;
      boolean asis = true;
      for (Object element : set) {
        if (!openType.isValue(element)) {
          asis = false;
          break;
        }
      }
      if (asis) {
        return cast(set);
      }
      coll = set;
    } else if (x instanceof Object[]) {
      coll = Arrays.asList((Object[]) x);
    } else {
      final String msg =
          "Descriptor value for " + name + " must be a Set or " +
              "an array: " + x.getClass().getName();
      throw new IllegalArgumentException(msg);
    }

    Set<T> result = new HashSet<T>();
    for (Object element : coll) {
      result.add(convertFrom(element, openType));
    }
    return result;
  }

  static <T> Comparable<?> comparableValueFrom(Descriptor d, String name,
      OpenType<T> openType) {
    T t = valueFrom(d, name, openType);
    if (t == null || t instanceof Comparable<?>) {
      return (Comparable<?>) t;
    }
    final String msg =
        "Descriptor field " + name + " with value " + t +
            " is not Comparable";
    throw new IllegalArgumentException(msg);
  }

  private static <T> T convertFrom(Object x, OpenType<T> openType) {
    if (openType.isValue(x)) {
      T t = OpenMBeanAttributeInfoSupport.<T>cast(x);
      return t;
    }
    return convertFromStrings(x, openType);
  }

  private static <T> T convertFromStrings(Object x, OpenType<T> openType) {
    if (openType instanceof ArrayType<?>) {
      return convertFromStringArray(x, openType);
    } else if (x instanceof String) {
      return convertFromString((String) x, openType);
    }
    final String msg =
        "Cannot convert value " + x + " of type " +
            x.getClass().getName() + " to type " + openType.getTypeName();
    throw new IllegalArgumentException(msg);
  }

  private static <T> T convertFromString(String s, OpenType<T> openType) {
    Class<T> c;
    try {
      ReflectUtil.checkPackageAccess(openType.safeGetClassName());
      c = cast(Class.forName(openType.safeGetClassName()));
    } catch (ClassNotFoundException e) {
      throw new NoClassDefFoundError(e.toString());  // can't happen
    }

    // Look for: public static T valueOf(String)
    Method valueOf;
    try {
      // It is safe to call this plain Class.getMethod because the class "c"
      // was checked before by ReflectUtil.checkPackageAccess(openType.safeGetClassName());
      valueOf = c.getMethod("valueOf", String.class);
      if (!Modifier.isStatic(valueOf.getModifiers()) ||
          valueOf.getReturnType() != c) {
        valueOf = null;
      }
    } catch (NoSuchMethodException e) {
      valueOf = null;
    }
    if (valueOf != null) {
      try {
        return c.cast(MethodUtil.invoke(valueOf, null, new Object[]{s}));
      } catch (Exception e) {
        final String msg =
            "Could not convert \"" + s + "\" using method: " + valueOf;
        throw new IllegalArgumentException(msg, e);
      }
    }

    // Look for: public T(String)
    Constructor<T> con;
    try {
      // It is safe to call this plain Class.getConstructor because the class "c"
      // was checked before by ReflectUtil.checkPackageAccess(openType.safeGetClassName());
      con = c.getConstructor(String.class);
    } catch (NoSuchMethodException e) {
      con = null;
    }
    if (con != null) {
      try {
        return con.newInstance(s);
      } catch (Exception e) {
        final String msg =
            "Could not convert \"" + s + "\" using constructor: " + con;
        throw new IllegalArgumentException(msg, e);
      }
    }

    throw new IllegalArgumentException("Don't know how to convert " +
        "string to " +
        openType.getTypeName());
  }


  /* A Descriptor contained an array value encoded as Strings.  The
     Strings must be organized in an array corresponding to the desired
     array.  If the desired array has n dimensions, so must the String
     array.  We will convert element by element from String to desired
     component type. */
  private static <T> T convertFromStringArray(Object x,
      OpenType<T> openType) {
    ArrayType<?> arrayType = (ArrayType<?>) openType;
    OpenType<?> baseType = arrayType.getElementOpenType();
    int dim = arrayType.getDimension();
    String squareBrackets = "[";
    for (int i = 1; i < dim; i++) {
      squareBrackets += "[";
    }
    Class<?> stringArrayClass;
    Class<?> targetArrayClass;
    try {
      stringArrayClass =
          Class.forName(squareBrackets + "Ljava.lang.String;");
      targetArrayClass =
          Class.forName(squareBrackets + "L" + baseType.safeGetClassName() +
              ";");
    } catch (ClassNotFoundException e) {
      throw new NoClassDefFoundError(e.toString());  // can't happen
    }
    if (!stringArrayClass.isInstance(x)) {
      final String msg =
          "Value for " + dim + "-dimensional array of " +
              baseType.getTypeName() + " must be same type or a String " +
              "array with same dimensions";
      throw new IllegalArgumentException(msg);
    }
    OpenType<?> componentOpenType;
    if (dim == 1) {
      componentOpenType = baseType;
    } else {
      try {
        componentOpenType = new ArrayType<T>(dim - 1, baseType);
      } catch (OpenDataException e) {
        throw new IllegalArgumentException(e.getMessage(), e);
        // can't happen
      }
    }
    int n = Array.getLength(x);
    Object[] targetArray = (Object[])
        Array.newInstance(targetArrayClass.getComponentType(), n);
    for (int i = 0; i < n; i++) {
      Object stringish = Array.get(x, i);  // String or String[] etc
      Object converted =
          convertFromStrings(stringish, componentOpenType);
      Array.set(targetArray, i, converted);
    }
    return OpenMBeanAttributeInfoSupport.<T>cast(targetArray);
  }

  @SuppressWarnings("unchecked")
  static <T> T cast(Object x) {
    return (T) x;
  }

  /**
   * Returns the open type for the values of the attribute described
   * by this {@code OpenMBeanAttributeInfoSupport} instance.
   */
  public OpenType<?> getOpenType() {
    return openType;
  }

  /**
   * Returns the default value for the attribute described by this
   * {@code OpenMBeanAttributeInfoSupport} instance, if specified,
   * or {@code null} otherwise.
   */
  public Object getDefaultValue() {

    // Special case for ArrayType and TabularType
    // [JF] TODO: clone it so that it cannot be altered,
    // [JF] TODO: if we decide to support defaultValue as an array itself.
    // [JF] As of today (oct 2000) it is not supported so
    // defaultValue is null for arrays. Nothing to do.

    return defaultValue;
  }

  /**
   * Returns an unmodifiable Set of legal values for the attribute
   * described by this {@code OpenMBeanAttributeInfoSupport}
   * instance, if specified, or {@code null} otherwise.
   */
  public Set<?> getLegalValues() {

    // Special case for ArrayType and TabularType
    // [JF] TODO: clone values so that they cannot be altered,
    // [JF] TODO: if we decide to support LegalValues as an array itself.
    // [JF] As of today (oct 2000) it is not supported so
    // legalValues is null for arrays. Nothing to do.

    // Returns our legalValues Set (set was constructed unmodifiable)
    return (legalValues);
  }

  /**
   * Returns the minimal value for the attribute described by this
   * {@code OpenMBeanAttributeInfoSupport} instance, if specified,
   * or {@code null} otherwise.
   */
  public Comparable<?> getMinValue() {

    // Note: only comparable values have a minValue,
    // so that's not the case of arrays and tabulars (always null).

    return minValue;
  }

  /**
   * Returns the maximal value for the attribute described by this
   * {@code OpenMBeanAttributeInfoSupport} instance, if specified,
   * or {@code null} otherwise.
   */
  public Comparable<?> getMaxValue() {

    // Note: only comparable values have a maxValue,
    // so that's not the case of arrays and tabulars (always null).

    return maxValue;
  }

  /**
   * Returns {@code true} if this {@code
   * OpenMBeanAttributeInfoSupport} instance specifies a non-null
   * default value for the described attribute, {@code false}
   * otherwise.
   */
  public boolean hasDefaultValue() {

    return (defaultValue != null);
  }

  /**
   * Returns {@code true} if this {@code
   * OpenMBeanAttributeInfoSupport} instance specifies a non-null
   * set of legal values for the described attribute, {@code false}
   * otherwise.
   */
  public boolean hasLegalValues() {

    return (legalValues != null);
  }

  /**
   * Returns {@code true} if this {@code
   * OpenMBeanAttributeInfoSupport} instance specifies a non-null
   * minimal value for the described attribute, {@code false}
   * otherwise.
   */
  public boolean hasMinValue() {

    return (minValue != null);
  }

  /**
   * Returns {@code true} if this {@code
   * OpenMBeanAttributeInfoSupport} instance specifies a non-null
   * maximal value for the described attribute, {@code false}
   * otherwise.
   */
  public boolean hasMaxValue() {

    return (maxValue != null);
  }


  /**
   * Tests whether {@code obj} is a valid value for the attribute
   * described by this {@code OpenMBeanAttributeInfoSupport}
   * instance.
   *
   * @param obj the object to be tested.
   * @return {@code true} if {@code obj} is a valid value for the parameter described by this {@code
   * OpenMBeanAttributeInfoSupport} instance, {@code false} otherwise.
   */
  public boolean isValue(Object obj) {
    return isValue(this, obj);
  }

  @SuppressWarnings({"unchecked", "rawtypes"})  // cast to Comparable
  static boolean isValue(OpenMBeanParameterInfo info, Object obj) {
    if (info.hasDefaultValue() && obj == null) {
      return true;
    }
    return
        info.getOpenType().isValue(obj) &&
            (!info.hasLegalValues() || info.getLegalValues().contains(obj)) &&
            (!info.hasMinValue() ||
                ((Comparable) info.getMinValue()).compareTo(obj) <= 0) &&
            (!info.hasMaxValue() ||
                ((Comparable) info.getMaxValue()).compareTo(obj) >= 0);
  }

    /* ***  Commodity methods from java.lang.Object  *** */


  /**
   * Compares the specified {@code obj} parameter with this {@code
   * OpenMBeanAttributeInfoSupport} instance for equality.
   * <p>
   * Returns {@code true} if and only if all of the following statements are true:
   * <ul>
   * <li>{@code obj} is non null,</li>
   * <li>{@code obj} also implements the {@code OpenMBeanAttributeInfo} interface,</li>
   * <li>their names are equal</li>
   * <li>their open types are equal</li>
   * <li>their access properties (isReadable, isWritable and isIs) are equal</li>
   * <li>their default, min, max and legal values are equal.</li>
   * </ul>
   * This ensures that this {@code equals} method works properly for
   * {@code obj} parameters which are different implementations of
   * the {@code OpenMBeanAttributeInfo} interface.
   *
   * <p>If {@code obj} also implements {@link DescriptorRead}, then its
   * {@link DescriptorRead#getDescriptor() getDescriptor()} method must
   * also return the same value as for this object.</p>
   *
   * @param obj the object to be compared for equality with this {@code
   * OpenMBeanAttributeInfoSupport} instance.
   * @return {@code true} if the specified object is equal to this {@code
   * OpenMBeanAttributeInfoSupport} instance.
   */
  public boolean equals(Object obj) {
    if (!(obj instanceof OpenMBeanAttributeInfo)) {
      return false;
    }

    OpenMBeanAttributeInfo other = (OpenMBeanAttributeInfo) obj;

    return
        this.isReadable() == other.isReadable() &&
            this.isWritable() == other.isWritable() &&
            this.isIs() == other.isIs() &&
            equal(this, other);
  }

  static boolean equal(OpenMBeanParameterInfo x1, OpenMBeanParameterInfo x2) {
    if (x1 instanceof DescriptorRead) {
      if (!(x2 instanceof DescriptorRead)) {
        return false;
      }
      Descriptor d1 = ((DescriptorRead) x1).getDescriptor();
      Descriptor d2 = ((DescriptorRead) x2).getDescriptor();
      if (!d1.equals(d2)) {
        return false;
      }
    } else if (x2 instanceof DescriptorRead) {
      return false;
    }

    return
        x1.getName().equals(x2.getName()) &&
            x1.getOpenType().equals(x2.getOpenType()) &&
            (x1.hasDefaultValue() ?
                x1.getDefaultValue().equals(x2.getDefaultValue()) :
                !x2.hasDefaultValue()) &&
            (x1.hasMinValue() ?
                x1.getMinValue().equals(x2.getMinValue()) :
                !x2.hasMinValue()) &&
            (x1.hasMaxValue() ?
                x1.getMaxValue().equals(x2.getMaxValue()) :
                !x2.hasMaxValue()) &&
            (x1.hasLegalValues() ?
                x1.getLegalValues().equals(x2.getLegalValues()) :
                !x2.hasLegalValues());
  }

  /**
   * <p>Returns the hash code value for this {@code
   * OpenMBeanAttributeInfoSupport} instance.</p>
   *
   * <p>The hash code of an {@code OpenMBeanAttributeInfoSupport}
   * instance is the sum of the hash codes of all elements of
   * information used in {@code equals} comparisons (ie: its name,
   * its <i>open type</i>, its default, min, max and legal
   * values, and its Descriptor).
   *
   * <p>This ensures that {@code t1.equals(t2)} implies that {@code
   * t1.hashCode()==t2.hashCode()} for any two {@code
   * OpenMBeanAttributeInfoSupport} instances {@code t1} and {@code
   * t2}, as required by the general contract of the method {@link
   * Object#hashCode() Object.hashCode()}.
   *
   * <p>However, note that another instance of a class implementing
   * the {@code OpenMBeanAttributeInfo} interface may be equal to
   * this {@code OpenMBeanAttributeInfoSupport} instance as defined
   * by {@link #equals(java.lang.Object)}, but may have a different
   * hash code if it is calculated differently.
   *
   * <p>As {@code OpenMBeanAttributeInfoSupport} instances are
   * immutable, the hash code for this instance is calculated once,
   * on the first call to {@code hashCode}, and then the same value
   * is returned for subsequent calls.
   *
   * @return the hash code value for this {@code OpenMBeanAttributeInfoSupport} instance
   */
  public int hashCode() {

    // Calculate the hash code value if it has not yet been done
    // (ie 1st call to hashCode())
    //
    if (myHashCode == null) {
      myHashCode = hashCode(this);
    }

    // return always the same hash code for this instance (immutable)
    //
    return myHashCode.intValue();
  }

  static int hashCode(OpenMBeanParameterInfo info) {
    int value = 0;
    value += info.getName().hashCode();
    value += info.getOpenType().hashCode();
    if (info.hasDefaultValue()) {
      value += info.getDefaultValue().hashCode();
    }
    if (info.hasMinValue()) {
      value += info.getMinValue().hashCode();
    }
    if (info.hasMaxValue()) {
      value += info.getMaxValue().hashCode();
    }
    if (info.hasLegalValues()) {
      value += info.getLegalValues().hashCode();
    }
    if (info instanceof DescriptorRead) {
      value += ((DescriptorRead) info).getDescriptor().hashCode();
    }
    return value;
  }

  /**
   * Returns a string representation of this
   * {@code OpenMBeanAttributeInfoSupport} instance.
   * <p>
   * The string representation consists of the name of this class (i.e.
   * {@code javax.management.openmbean.OpenMBeanAttributeInfoSupport}),
   * the string representation of the name and open type of the
   * described parameter, the string representation of its
   * default, min, max and legal values and the string
   * representation of its descriptor.
   *
   * <p>As {@code OpenMBeanAttributeInfoSupport} instances are
   * immutable, the string representation for this instance is
   * calculated once, on the first call to {@code toString}, and
   * then the same value is returned for subsequent calls.
   *
   * @return a string representation of this {@code OpenMBeanAttributeInfoSupport} instance.
   */
  public String toString() {

    // Calculate the string value if it has not yet been done
    // (ie 1st call to toString())
    //
    if (myToString == null) {
      myToString = toString(this);
    }

    // return always the same string representation for this
    // instance (immutable)
    //
    return myToString;
  }

  static String toString(OpenMBeanParameterInfo info) {
    Descriptor d = (info instanceof DescriptorRead) ?
        ((DescriptorRead) info).getDescriptor() : null;
    return
        info.getClass().getName() +
            "(name=" + info.getName() +
            ",openType=" + info.getOpenType() +
            ",default=" + info.getDefaultValue() +
            ",minValue=" + info.getMinValue() +
            ",maxValue=" + info.getMaxValue() +
            ",legalValues=" + info.getLegalValues() +
            ((d == null) ? "" : ",descriptor=" + d) +
            ")";
  }
}
